#include <iostream>
#include <string>
#include <vector>
using namespace std;

int exchange(int &val1, int &val2) {
  int a;
  a = val1;
  val1 = val2;
  val2 = a;
  return 0;
}
int main() {
  cout << "请输入需要交换的两整数:";
  int val1, val2;
  cin >> val1 >> val2;
  cout << "交换之前的两数：" << val1 << " " << val2 << endl;
  exchange(val1, val2);
  cout << "交换之后的两数：" << val1 << " " << val2 << endl;
}